Products · Composite Infrastructure

Composite (GRP/FRP) Covers, Grates, Channels and Pool Covers from Türkiye

Q: Are composite manhole covers as strong as cast iron?

For load classes A15, B125, C250 and D400 — covering pedestrian, residential, kerb and road use — composite covers are certified to the same EN 124 load requirements as cast iron and pass identical test loads. Composite is available up to class E600 in some ranges. For F900 (aircraft docks) cast iron remains the practical choice.

Q: Why is theft a reason to switch from cast iron to composite manhole covers?

A cast-iron manhole cover has significant scrap value, which drives systematic theft of covers from streets, telecom sites and unmanned infrastructure, creating a serious safety risk. A composite cover has no scrap value and is not stolen. This is one of the most common reasons municipalities and telecom operators switch to composite.

Q: What is the difference between GRP and FRP?

GRP (Glass-fibre Reinforced Polymer) and FRP (Fibre Reinforced Polymer) refer to the same family of composite materials. GRP specifies that the reinforcing fibre is glass; FRP is the broader term that also covers carbon-fibre and aramid composites. For infrastructure covers and grates the material is almost always GRP.

Steeling supplies a full range of composite infrastructure products manufactured in Türkiye — manhole covers, rainwater grates, residential covers, cable junction chambers, drainage channels and pool/tank covers — produced from glass-fibre-reinforced polymer (GRP/FRP) to EN 124-5 load classes. Composite products replace cast iron and steel where corrosion, theft, weight or electromagnetic requirements make metal the wrong material.

Request a Quotation See Metal Grates & Drainage

What are composite infrastructure products?

Composite infrastructure products are covers, grates, channels and chambers manufactured from glass-fibre-reinforced polymer (GRP/FRP) — typically using Sheet Moulding Compound (SMC) or Bulk Moulding Compound (BMC) hot-press moulding with unsaturated polyester resin, silica sand filler and glass-fibre reinforcement. They are the direct functional replacement for cast iron and steel covers and grates in manholes, drainage systems, cable networks, water tanks and technical pools, tested and certified to the same load classes.

Why composite instead of metal — six reasons buyers switch

No scrap value

Composite covers have no resale value as scrap. In areas where cast-iron manhole covers are stolen for scrap, composite covers stay in place — critical for telecom sites, remote infrastructure and unmanned pumping stations.

Corrosion-proof

Immune to salt water, chlorine, acids and most industrial chemicals. Standard choice for coastal, marine, chemical, food-processing and wastewater applications where cast iron rusts and stainless steel is expensive.

Light — 60–75% less mass

A composite D400 manhole cover weighs 20–35 kg versus 60–120 kg for cast iron. One person can lift and reset it. Freight cost per pallet drops proportionally.

Electromagnetically transparent

Non-metallic construction lets radio, RFID, GPS and inductive signals pass through. Required for telecom manhole covers over 5G/fibre nodes, radar-adjacent chambers, RF test facilities and inductive charging pads.

Non-magnetic

Ferromagnetic-free — safe for MRI facilities, precision-measurement labs, defence installations and any environment where a magnetic field must not be disturbed.

Low lifetime cost

No corrosion protection, no repainting, no rust replacement cycle. Design life is typically 25+ years in outdoor infrastructure use, and the covers do not seize into their frames.

Composite vs cast iron and steel — side-by-side

Factor	Composite (GRP/FRP)	Cast iron	Galvanised steel
Density (g/cm³)	1.8–2.0	7.2	7.8
D400 cover weight (600 mm)	25–35 kg	65–90 kg	55–80 kg
Corrosion resistance	Excellent	Poor	Moderate
Scrap value	None	High	Moderate
Electromagnetic transparency	Yes	No	No
Ferromagnetic	No	Yes	Yes
Chemical resistance	Broad	Limited	Limited
Design life outdoor	25+ years	15–30 years (with maintenance)	15–25 years
Repainting required	No	Yes	Yes
Load classes covered	A15 to E600	A15 to F900	A15 to D400

For heavy port and aircraft-apron applications (E600 and F900) cast iron and heavy steel still dominate; composite is competitive from pedestrian (A15) up to standard highway (D400). For the full metal range see the metal grates and drainage systems page.

Product range

Six product families, all supplied to project specification, with standard sizes ex-stock and custom sizes on order. Composite construction, EN 124-5 certified where applicable, ISO 9001 manufacturing.

Composite manhole covers

Square and round, hinged / lockable / gasket-sealed variants

Direct replacement for cast-iron manhole covers on municipal, telecom, water, electrical and industrial networks. Supplied with matching composite frame or as cover-only for retrofit.

Load classes:: A15 · B125 · C250 · D400
Standard:: TS EN 124-5 (composite covers)
Formats:: square 400×400 to 800×800, round Ø400 to Ø800
Variants:: plain · hinged · lockable · watertight (gasketed)

Composite rainwater grates

Kerb and gully grates for surface water collection

Rainwater grates for streets, sidewalks, car parks and industrial yards. Anti-slip surface pattern; grate + frame supplied as a set. Lower installed weight simplifies handling on long grate runs.

Load classes:: A15 · B125 · C250 · D400
Standard:: TS EN 124-5
Typical set:: 600 × 600 mm grate + frame
Slot opening:: compliant with EN 124 pedestrian-safety geometry

Composite residential & garden covers

Light-duty covers for private plots, gardens and pedestrian areas

Non-load and light-load covers for residential compounds, landscaped areas and pedestrian zones. Chosen for weight, aesthetics and freedom from rust staining around cover perimeters.

Load classes:: B125 · C250
Formats:: 600 × 800 mm, 800 × 800 mm
Colour:: black standard; custom colours on order

Composite cable junction chambers

Underground enclosures for electrical, telecom and fibre joints

Underground chambers protect cable joints from water ingress, impact and corrosion. Composite construction is standard for fibre-optic and 5G junction boxes because signals pass through the chamber wall and cover.

Standard size:: 485 × 485 × 410 mm
Variants:: six configurations with different cover types and cable entries
Sealing:: IP-rated cover options available

Composite drainage channels

Linear surface-water collection channels with composite grate

Complete linear drainage systems — composite channel body with matching composite grate — for surface water collection on paved areas, industrial floors, car parks and around swimming pools. The composite grate does not stain the surrounding paving.

Standard size:: 300 × 1000 × 200 mm (W × L × H)
Load classes:: A15 · B125 · C250
Connection:: modular end-to-end coupling with side and bottom outlets

Composite pool & tank covers

Metal-free covers for water tanks, technical pools, cisterns

Composite covers for water storage tanks, technical pools, reservoirs and cistern access points. Chosen where corrosion, theft resistance or hygiene rules make metal covers unsuitable — hotels, water utilities, chemical dosing tanks, cooling-water reservoirs, industrial CIP tanks.

Standard sizes:: 550, 650, 700, 800, 900, 1050 mm (square)
Construction:: hot-press moulded, metal-free body, gasket-sealed hinged variant
Custom sizes:: rectangular and non-standard formats on order
Features:: corrosion-proof · anti-theft · lightweight · low maintenance

EN 124 load classes — how to specify the right cover

EN 124 defines six load classes for manhole covers and gully tops based on where they will be installed and the wheel loads they must withstand. TS EN 124-5 is the specific part of the standard that covers composite (non-metallic) covers, using the same load classification.

Class	Test load	Where it goes	Composite available?
A15	15 kN	Footways, pedestrian areas, cycle paths	Yes
B125	125 kN	Sidewalks, private car parks, residential driveways	Yes
C250	250 kN	Kerb areas, gully tops up to 0.5 m from the kerb	Yes
D400	400 kN	Roads, hard shoulders, car-park lanes for all vehicles	Yes
E600	600 kN	Docks, aircraft pavements, heavy-duty pavements	Limited
F900	900 kN	Aircraft docks, extreme-load pavements	Cast iron only

Sectors that specify composite over metal

Telecom & fibre infrastructure5G and fibre chambers, base-station manholes — signal transparency and anti-theft.

Water & wastewaterCorrosion-proof covers over sewers, pumping stations, treatment plants.

Marine, ports & coastalSalt-air and salt-water exposure destroys cast iron; composite is standard.

Chemical & petrochemicalAcid, base and solvent resistance for process-area drainage.

Food & beverage plantsHygienic, non-rusting drainage and floor covers around wet processing.

Hospitality & leisurePool decks, spa areas, hotel technical rooms — composite pool covers and pool-deck drainage.

Municipal & utility networksAnti-theft solution for cover loss in urban and remote areas.

Defence & sensitive facilitiesNon-magnetic and RF-transparent covers for restricted-material zones.

Sourcing composite infrastructure products from Türkiye

Türkiye has a well-developed composite manufacturing base for infrastructure products, with SMC and BMC press capacity, TS EN 124-5 certification and export experience across Europe, the Middle East and North Africa. Steeling consolidates orders across product families so a single project can source composite manhole covers, rainwater grates, drainage channels and pool covers from one purchase order rather than several separate suppliers. Sourcing service is free of charge for international buyers — the same platform model described in how to source metal (and composite) products from Türkiye.

Need the metal counterpart? See our metal grates, covers and drainage systems for cast-iron, galvanised-steel and stainless-steel options.

Frequently asked questions

What is a composite manhole cover made from?

A composite manhole cover is made from glass-fibre-reinforced polymer (GRP/FRP), usually manufactured by Sheet Moulding Compound (SMC) or Bulk Moulding Compound (BMC) hot-press moulding. The base material is unsaturated polyester resin, reinforced with chopped glass fibre and filled with silica sand and mineral fillers to reach the required strength and load class.

Are composite manhole covers as strong as cast iron?

For the load classes A15, B125, C250 and D400 — which cover pedestrian, residential, kerb and road use — composite covers are certified to the same EN 124 load requirements as cast iron and pass identical test loads. Composite is available up to class E600 in some ranges. For F900 (aircraft docks, extreme-load pavements) cast iron remains the practical choice.

Why is theft a reason to switch from cast iron to composite?

A cast-iron manhole cover has significant scrap value — in many countries this drives systematic theft of covers from streets, telecom sites and unmanned infrastructure, creating a serious safety risk. A composite cover has no scrap value and is not stolen. This is one of the most common reasons municipalities and telecom operators switch to composite.

Are composite covers approved for use on highways?

Yes. Composite manhole covers and gully tops certified to TS EN 124-5 in class D400 are approved for use on carriageways, hard shoulders and all vehicle areas of roads. The load class, not the material, determines where a cover may be installed.

Do composite covers work for 5G and fibre-optic infrastructure?

Yes — composite covers are the standard choice for 5G, small-cell and fibre-optic junction chambers because they are electromagnetically transparent. Radio, RFID and inductive signals pass through the composite cover, which allows the equipment inside the chamber to communicate without a fixed metallic aperture in the way.

What is the difference between GRP and FRP?

GRP (Glass-fibre Reinforced Polymer or Plastic) and FRP (Fibre Reinforced Polymer or Plastic) refer to the same family of composite materials. GRP specifies that the reinforcing fibre is glass; FRP is the broader term that also covers carbon-fibre and aramid composites. For infrastructure covers and grates the material is almost always GRP.

What sizes of composite pool cover are available?

Standard square sizes are 550, 650, 700, 800, 900 and 1050 mm side length. Custom sizes and rectangular formats are produced on order for water storage tanks, technical pools, reservoirs and cistern openings. Hinged and gasket-sealed variants are available for watertight applications.

How much lighter is a composite manhole cover than a cast-iron one?

For a Ø600 mm D400 cover, composite weighs approximately 25–35 kg versus 65–90 kg for cast iron — a reduction of about 60–70%. This means one person can typically lift and reset a composite cover safely, whereas the cast-iron equivalent needs two people or a lifting tool.

Does Steeling install the covers as well as supply them?

Steeling primarily supplies the product for installation by the site contractor. On projects that include a broader supply-and-install scope — for example a full facade or drainage package — installation can be arranged through Steeling's applicator network. Contact Steeling with the project scope for a specific answer.

Which certifications come with the products?

Composite covers and grates are supplied with TS EN 124-5 test certification for the declared load class, ISO 9001 manufacturing certification, and CE Declaration of Performance where the product falls under a harmonised European standard. Product datasheets, load test reports and material safety information are provided on request.

Get a quote for composite covers, grates or pool covers

Send project size, load class and delivery destination. You will receive a firm offer from Turkish composite manufacturers, free of charge to the buyer.

Request a Quotation See Metal Grates & Drainage